Fractal Characteristics Of Road Network Structure Of "Small Block,Dense Road Network" Space Model

As the process of rapid urbanization in various countries in the world continues to progress,the reduction of global resources,the increase of population,the intensification of the contradictions between man and nature,the shrinking of living space and the tense relationship between man and land have taken place.As a result,cities have grown smartly in limited spaces,and the adoption of a compact model of development has gradually become the consensus of global cities today and in the future.In recent years,domestic scholars have started to recognize and constantly reflect on the shortcomings of the spatial pattern of "big road network",and at the same time,actively explore the advantages of the foreign "small block" space model.In 2016,the state released important documents and advocated the development of the model of "Block system".Thus,the "small block" model will become an important model of urban space in China's future urban development.In the past,scholars tended to study the road capacity,but lacked the research on the road network structure.It seems that traffic jams need to be repaired,narrow roads need to be widened and widened,which has become a fixed "governance" model.Combined with practice,it can be seen that simply expanding the road capacity can not alleviate the traffic problem,and perhaps a perfect road network structure can only be achieved.Therefore,it is necessary to further study the structural characteristics of road network.At present,domestic scholars mostly study and analyze the "small block" spatial model from the qualitative point of view,and lack quantitative analysis.Therefore,this paper takes the " Small block,dense road network " spatial model road network structure as the research object,takes the fractal theory as the research tool,analyzes the "small block" spatial model from the quantitative point of view.The structural characteristics of the road network.Firstly,the paper obtains the road network data of many urban centers and core districts in China and foreign countries,such as Rome,Portland,Xi'an and Shanghai;Secondly,it studies the basic spatial characteristics and the fractal characteristics of the road network structure of the case,and takes the urban road network structure of each case as an example.The calculation and analysis of fractal dimension value is the focus of the study.The differences of road network structure in different cases are classified and summarized from the perspective of fractal theory.After calculating the box dimension,length-radius dimension and branching dimension of the road network in each case,it is concluded that the spatial model of " Small block,dense road network " is closer to the ideal network structure of fractal theory,and has better coverage,saturation and accessibility than the spatial model of " big road network ".At the same time,from the calculation results,the optimal fractal dimension values of the ideal street network are obtained.In addition,combined with the different fractal dimension of fractal theory can reflect the different characteristics of road network structure,this paper attempts to establish an index system based on fractal dimension to evaluate road network structure characteristics,in order to make up for the current specifications,single index and insufficient guidance to the layout of urban road network structure,and guide the city in the future.The continuous improvement and perfection of the urban road network structure design.Finally,the fractal theory analysis method is used to study the road network structure of the five edition of the core area of Chenggong New Area in Kunming.The fractal dimension of the road network structure of each edition of the planning scheme is analyzed.The structural characteristics of the road network of each edition of the planning scheme are summarized with the calculation results,and the change trend of the fractal characteristics of the road network structure is analyzed.The evaluation of the scheme road network structure shows that the fractal analysis method can be applied to the practical value of scheme selection.